Bernard S. Levowitz

Pathophysiologic effects of bowel distention on intestinal blood flow

Abstract 1.1. The effects of acute bowel distention on intestinal circulation were studied in dogs. 2.2. Intraluminal pressures at or above 30 mm. Hg produced a consistent immediate fall in intestinal blood flow. Higher pressures produced correspondingly greater diminutions in flow until an irreducible 20 to 35 per cent of flow remained. 3.3. As blood flow fell, there was an associated decrease in the arteriovenous oxygen difference indicating diminished oxygen extraction by the intestine. 4.4. Injection studies performed in situ with increasing intraluminal pressures showed filling of only the submucosal and serosal vessels with pressures at or above 60 to 90 mm. Hg. 5.5. Krypton 85 washout studies are compatible with a shift of blood flow away from the mucosa at intraluminal pressures above 60 mm. Hg. 6.6. These findings indicate that above an intraluminal pressure of 30 mm. Hg, blood is shunted through functional or anatomic arteriovenous communications depriving the bowel mucosa. 7.7. The roles of increased intraluminal pressure, intestinal ischemia, and hypoxia are discussed as accounting for the colitis seen proximal to colonic neoplasms.

Traumatic mesenteric arteriovenous fistula

Abstract A case of traumatic mesenteric arteriovenous fistula is presented. The clinical and angiographic findings are reviewed and discussed. Early recognition of the fistula is of utmost importance. Arteriography is essential for confirmation of the diagnosis and localisation of the lesion. Selective superior mesenteric arteriography is recommended in all suspected cases. Reprints of this article can be obtained from Rubem Pochaczevsky, M.D., Department of Radiology, Greenpoint Hospital Affiliation, The Jewish Hospital and Medical Center of Brooklyn, 300 Skillman Avenue, Brooklyn, N.Y., 11211, U.S.A.

Thrombus formation at the mitral annulus caused by prosthetic rings. An experimental study.

Abstract In twenty dogs simple rings of Ivalon, Dacron, Silastic and Silastic covered by arterial homograft were implanted at the annulus of the intact mitral valve. Fifteen animals demonstrated an atrial thrombus associated with peripheral embolization. Thrombotic occlusion of the mitral orifice accounted for the death of fourteen animals. Encasement of Silastic rings in the arterial homograft appeared to suppress clot formation and prolonged the survival of three of five dogs. At the level of ring fixation, the inflammatory changes in the atrial wall and the presence of bacteria within the adherent thrombus were consistent findings which simulated acute bacterial endocarditis. The problem of prosthetic replacement of the mitral valve is discussed in the light of these experimental observations.

Heterograft biocompatibility without proteolytic digestion.

Bovine and sheep carotid heterografts (BED and S-ED) were modified by sequential treatment with 95% ethanol and 1.3% dialdehyde starch and stored in 70% ethanol. Compared with ficin digested, dialdehyde tanned bovine carotid artery (B-FD), chemical treatment produced heterografts with greater in vitro anastomotic tensile strength and significantly reduced surface clotting time. Seven of 20 canine inferior caval implants of B-ED heterografts remained patent for periods up to 4 weeks while 4 of 5 B-FD interpositions thrombosed within 2 hr. A patency rate of over 90% was obtained in canine abdominal and thoracic aorta B-ED and S-ED interpositions during a follow up period of 3 to 6 months. As arteriovenous fistulas B-ED heterografts maintained excellent patency, tolerated repetitive percutaneous puncture and exhibited self sealing capability. Microscopic examination of longterm B-ED implants showed smooth intimal surfaces with no fibrin deposition or morphologic evidence of rejection. In contrast to the ficin digested heterograft, ethanol-dialdehyde processing suppresses antigenic potential but preserves structural integrity. The end product retains components of the heterograft wall and results in a nonviable, biocompatible conduit with improved thromboresistance and greater strength.

Nodal response in medullary carcinoma of the breast

From 1954 to 1970, ninety-five patients with medullary carcinoma of the breast were evaluated in terms of immunologic activity based on the histologic changes seen within the tumor and regional nodes. Each patient was studied for the degree of lymphocytic infiltration in the tumor as well as the extent of sinus histiocytosis present within the regional nodes. Contrary to what would normally be expected, those nodes with increased sinus histiocytosis were associated with the larger tumors. In addition, lymph node metastasis increased from 26 to 75 per cent as the degree of sinus histiocytosis became more pronounced. There was no evidence that increased lymphocytic infiltration in the tumor resulted in a statistically significant improvement in the five and ten year survival rates. Similarly, sinus histiocytosis activity did not seem to enhance the survival rate among this particular group of patients. There is a suggestion that a correlation exists between sinus histiocytosis and lymphocytic infiltration in the tumor and that, whatever the stimulus present, its effect is on both the lymph node and the degree of lymphocyte response within the tumor. The antigenic substance in the tumor, which initiates the immune response, possibly produces an abortive reaction, which may result in the induction of blocking factors rather then those factors necessary for destruction. It appears that histologic evidence of immunologic enhancement does not necessarily signify improved survival, at least with those patients having carcinoma of the breast.